diff --git a/src/bors/handlers/workflow.rs b/src/bors/handlers/workflow.rs
index 2e99ca22..054133f3 100644
--- a/src/bors/handlers/workflow.rs
+++ b/src/bors/handlers/workflow.rs
@@ -691,4 +691,27 @@ min_ci_time = 20
         })
         .await;
     }
+
+    #[sqlx::test(migrator = "crate::MIGRATOR")]
+    async fn ignore_pull_request_event_workflow(pool: sqlx::PgPool) {
+        run_test(pool.clone(), async |ctx: &mut BorsTester| {
+            ctx.post_comment("@bors try").await?;
+            ctx.expect_comments((), 1).await;
+
+            let workflow = ctx.try_workflow();
+            ctx.modify_workflow(workflow, |run| {
+                run.set_event("pull_request");
+            });
+
+            ctx.skip_waiting_for_marker(async |ctx| {
+                ctx.workflow_event(WorkflowEvent::started(workflow)).await?;
+                ctx.workflow_event(WorkflowEvent::success(workflow)).await
+            })
+            .await?;
+
+            Ok(())
+        })
+        .await;
+        assert!(get_all_workflows(&pool).await.unwrap().is_empty());
+    }
 }
diff --git a/src/server/webhook.rs b/src/server/webhook.rs
index 577ac8aa..5572d1f8 100644
--- a/src/server/webhook.rs
+++ b/src/server/webhook.rs
@@ -335,6 +335,14 @@ fn parse_pull_request_review_comment_events(body: &[u8]) -> anyhow::Result<Optio
 fn parse_workflow_run_events(body: &[u8]) -> anyhow::Result<Option<BorsEvent>> {
     let payload: WebhookWorkflowRun = serde_json::from_slice(body)?;
     let repository_name = parse_repository_name(&payload.repository)?;
+
+    // As a security precaution, we eagerly prefilter all workflow runs other than "push" here,
+    // to ensure that only workflows from privileged pushes to branches in the repository are
+    // registered by bors.
+    if payload.workflow_run.run.event != "push" {
+        return Ok(None);
+    }
+
     let result = match payload.action {
         "requested" => Some(BorsEvent::Repository(BorsRepositoryEvent::WorkflowStarted(
             WorkflowRunStarted {
diff --git a/src/tests/github.rs b/src/tests/github.rs
index 26f171d8..1097a028 100644
--- a/src/tests/github.rs
+++ b/src/tests/github.rs
@@ -1117,6 +1117,7 @@ pub struct WorkflowRun {
     /// How long did the workflow run for?
     duration: Duration,
     status: WorkflowStatus,
+    event: String,
 }
 
 impl WorkflowRun {
@@ -1130,6 +1131,7 @@ impl WorkflowRun {
             jobs: vec![],
             head_sha: branch.sha(),
             duration: Duration::from_secs(3600),
+            event: "push".to_string(),
         }
     }
 
@@ -1172,6 +1174,13 @@ impl WorkflowRun {
         self.status
     }
 
+    pub fn event(&self) -> &str {
+        &self.event
+    }
+    pub fn set_event(&mut self, event: &str) {
+        self.event = event.to_string();
+    }
+
     pub fn add_job(&mut self, status: WorkflowStatus) {
         self.jobs.push(WorkflowJob {
             id: JobId(self.run_id.0 * 1000 + self.jobs.len() as u64),
diff --git a/src/tests/mock/workflow.rs b/src/tests/mock/workflow.rs
index ba9f96a7..f791f9e7 100644
--- a/src/tests/mock/workflow.rs
+++ b/src/tests/mock/workflow.rs
@@ -95,7 +95,7 @@ impl GitHubWorkflowRun {
             head_branch: run.head_branch().to_owned(),
             head_sha: run.head_sha().to_owned(),
             run_number: 0,
-            event: "".to_string(),
+            event: run.event().to_string(),
             status,
             conclusion,
             created_at,
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index d3dd6128..7e52dc82 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -195,6 +195,7 @@ pub struct BorsTester {
     mergeability_queue_rx: MergeabilityQueueReceiver,
     gitops_queue_rx: GitOpsQueueReceiver,
     ctx: Arc<BorsContext>,
+    wait_for_markers: bool,
 }
 
 impl BorsTester {
@@ -267,6 +268,7 @@ impl BorsTester {
                 mergeability_queue_rx,
                 gitops_queue_rx,
                 ctx,
+                wait_for_markers: true,
             },
             bors,
         )
@@ -525,6 +527,7 @@ impl BorsTester {
                     .unwrap();
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_BUILD_QUEUE,
         )
         .await
@@ -542,6 +545,7 @@ impl BorsTester {
                     .unwrap();
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_MERGEABILITY_STATUS_REFRESH,
         )
         .await
@@ -558,6 +562,7 @@ impl BorsTester {
                     .unwrap();
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_PR_STATUS_REFRESH,
         )
         .await
@@ -577,6 +582,7 @@ impl BorsTester {
                 self.senders.merge_queue().perform_tick().await.unwrap();
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_MERGE_QUEUE,
         )
         .await
@@ -592,6 +598,7 @@ impl BorsTester {
                     .unwrap();
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_MERGE_QUEUE,
         )
         .await
@@ -1180,6 +1187,7 @@ impl BorsTester {
                 );
                 Ok(())
             },
+            self.wait_for_markers,
             &WAIT_FOR_WEBHOOK_COMPLETED,
         )
         .await?;
@@ -1196,6 +1204,18 @@ impl BorsTester {
             .await
     }
 
+    /// Run the provided async function while not waiting for markers to be hit.
+    pub async fn skip_waiting_for_marker<F, R>(&mut self, func: F) -> R
+    where
+        F: AsyncFnOnce(&mut Self) -> R,
+    {
+        let orig = self.wait_for_markers;
+        self.wait_for_markers = false;
+        let res = func(self).await;
+        self.wait_for_markers = orig;
+        res
+    }
+
     async fn finish(self, bors: JoinHandle<()>) -> anyhow::Result<GitHub> {
         // Tell the mergeability queue that it should shutdown once it has nothing else to do
         self.senders.mergeability_queue().shutdown();
@@ -1519,7 +1539,11 @@ impl PullRequestProxy {
 
 /// Start an async operation and wait until a specific [`TestSyncMarker`]
 /// is marked.
-async fn wait_for_marker<Func, R>(func: Func, marker: &TestSyncMarker) -> anyhow::Result<R>
+async fn wait_for_marker<Func, R>(
+    func: Func,
+    wait: bool,
+    marker: &TestSyncMarker,
+) -> anyhow::Result<R>
 where
     Func: AsyncFnOnce() -> anyhow::Result<R>,
 {
@@ -1530,7 +1554,7 @@ where
     marker.drain().await;
 
     let res = func().await;
-    if res.is_ok() {
+    if wait && res.is_ok() {
         tokio::time::timeout(SYNC_MARKER_TIMEOUT, marker.sync())
             .await
             .map_err(|_| anyhow::anyhow!("Timed out waiting for a test marker to be marked"))?;